Glossary of linear algebra

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This is a glossary of linear algebra.

See also: glossary of module theory.


A

Affine transformation
A composition of functions consisting of a linear transformation between vector spaces followed by a translation.[1] Equivalently, a function between vector spaces that preserves affine combinations.
Affine combination
A linear combination in which the sum of the coefficients is 1.

B

Basis
In a vector space, a linearly independent set of vectors spanning the whole vector space.[2]
Basis vector
An element of a given basis of a vector space.[2]

C

Column vector
A matrix with only one column.[3]
Coordinate vector
The tuple of the coordinates of a vector on a basis.
Covector
An element of the dual space of a vector space, (that is a linear form), identified to an element of the vector space through an inner product.

D

Determinant
The unique scalar function over square matrices which is distributive over matrix multiplication, multilinear in the rows and columns, and takes the value of [math]\displaystyle{ 1 }[/math] for the unit matrix.
Diagonal matrix
A matrix in which only the entries on the main diagonal are non-zero.[4]
Dimension
The number of elements of any basis of a vector space.[2]
Dual space
The vector space of all linear forms on a given vector space.[5]

E

Elementary matrix
Square matrix that differs from the identity matrix by at most one entry

I

Identity matrix
A diagonal matrix all of the diagonal elements of which are equal to [math]\displaystyle{ 1 }[/math].[4]
Inverse matrix
Of a matrix [math]\displaystyle{ A }[/math], another matrix [math]\displaystyle{ B }[/math] such that [math]\displaystyle{ A }[/math] multiplied by [math]\displaystyle{ B }[/math] and [math]\displaystyle{ B }[/math] multiplied by [math]\displaystyle{ A }[/math] both equal the identity matrix.[4]
Isotropic vector
In a vector space with a quadratic form, a non-zero vector for which the form is zero.
Isotropic quadratic form
A vector space with a quadratic form which has a null vector.

L

Linear algebra
The branch of mathematics that deals with vectors, vector spaces, linear transformations and systems of linear equations.
Linear combination
A sum, each of whose summands is an appropriate vector times an appropriate scalar (or ring element).[6]
Linear dependence
A linear dependence of a tuple of vectors [math]\displaystyle{ \vec v_1,\ldots,\vec v_n }[/math] is a nonzero tuple of scalar coefficients [math]\displaystyle{ c_1,\ldots,c_n }[/math] for which the linear combination [math]\displaystyle{ c_1\vec v_1+\cdots+c_n\vec v_n }[/math] equals [math]\displaystyle{ \vec0 }[/math].
Linear equation
A polynomial equation of degree one (such as [math]\displaystyle{ x = 2y - 7 }[/math]).[7]
Linear form
A linear map from a vector space to its field of scalars[8]
Linear independence
Property of being not linearly dependent.[9]
Linear map
A function between vector spaces which respects addition and scalar multiplication.
Linear transformation
A linear map whose domain and codomain are equal; it is generally supposed to be invertible.

M

Matrix
Rectangular arrangement of numbers or other mathematical objects.[4]

N

Null vector
1.  Another term for an isotropic vector.
2.  Another term for a zero vector.

R

Row vector
A matrix with only one row.[4]

S

Singular-value decomposition
a factorization of an [math]\displaystyle{ m \times n }[/math] complex matrix M as [math]\displaystyle{ \mathbf{U\Sigma V^*} }[/math], where U is an [math]\displaystyle{ m \times m }[/math] complex unitary matrix, [math]\displaystyle{ \mathbf{\Sigma} }[/math] is an [math]\displaystyle{ m \times n }[/math] rectangular diagonal matrix with non-negative real numbers on the diagonal, and V is an [math]\displaystyle{ n \times n }[/math] complex unitary matrix.[10]
Spectrum
Set of the eigenvalues of a matrix.[11]
Square matrix
A matrix having the same number of rows as columns.[4]

U

Unit vector
a vector in a normed vector space whose norm is 1, or a Euclidean vector of length one.[12]

V

Vector
1.  A directed quantity, one with both magnitude and direction.
2.  An element of a vector space.[13]
Vector space
A set, whose elements can be added together, and multiplied by elements of a field (this is scalar multiplication); the set must be an abelian group under addition, and the scalar multiplication must be a linear map.[14]

Z

Zero vector
The additive identity in a vector space. In a normed vector space, it is the unique vector of norm zero. In a Euclidean vector space, it is the unique vector of length zero.[15]

Notes

References

  • James, Robert C.; James, Glenn (1992). Mathematics Dictionary (5th ed.). Chapman and Hall. ISBN 978-0442007416. 
  • Bourbaki, Nicolas (1989). Algebra I. Springer. ISBN 978-3540193739. 
  • Williams, Gareth (2014). Linear algebra with applications (8th ed.). Jones & Bartlett Learning.